Print developer



Jan. 20, 1953 D. R. L. CORNWELL ETAL 2,625,866

PRINT DEVELOPER Filed Aug. 5, 1949 2 SHEETS-SHEET l Jan. 20, 1953 D. R. CORNWIQILL ET AL 2,625,866

PRINT DEVELOPE 2 SHEETS 2 Filed 1949 Patented Jan. 20, 1953 UNITED STATES PATENT OFFICE PRINT DEVELOPER David L. Cornwell and John Tai'ni, Chicago,

Ill.-, assignors to The C. F. Pease Company, Chicago, 111., a corporation of Delaware a Application August 5, 1949, Serial No. 108,714

2 Claims. 1

This invention relates to improvements in gas print developers; that is, an apparatus for developing light sensitive prints by a gas such as ammonia.

Heretofore, the print has been exposed to the action of the gas by causing it to be advanced across a perforated wall of a chamber in which ammonia or other gas is being generated. This is accomplished by the use of an endless belt which slides over and across the perforated wall and causes the sensitized surface of the print to be held in contact therewith.

This prior art arrangement has certain objectionable features. For instance, the edges of the perforations cause excessive belt wear and due to the fact that only a small proportion of the area of the print is being exposed to the action of the gas at any one instant, the speed at which the print is advanced is limited. Also, when prints made of cellophane foil or of tracing cloth are passed through the machine, they tend to adhere to the plate instead of sliding smoothly over it. This is due to the fact that the periorated plate is necessarily at an elevated temperature, which causes the print to become tacky and stick to the plate.

It is an object of this invention to provide a print developer which eliminates the use of a perforated plate and in which any sliding motion of the sensitized surface of the print with respect to any other element is eliminated.

A further object is to provide a developer which is capable of high speed operation and in which belt wear is reduced to a minimum.

A still further object is to provide a developer which is designed so that it can be sold either as a separate unit, or as an integral component of a machine which both prints and develops.

Still another object is to provide an improved developer of comparatively simple and inexpensive construction.

With reference now to the drawings in which like reference numerals designate like parts:

Fig. 1 is a side elevation of a preferred embodiment of this invention, one of the side frames being partially broken away to show certain parts in section;

Fig. 2 is a front elevation of Fig. 1, partially broken away.

Fig. 3 is an enlarged elevation of one of the wheels which illustrates the cooperation of the parts;

Fig. 4 is a section taken along line 44 of Fig. 3;

Fig. 5 is a plan view of the marginal bottom 2 of the casing, taken generally along line 5-5 of Fig. 3, and also showing the relationship of the developed print which overlies the same;

Fig. 6 is a section taken along line G6 of Fig. 1 showing the means for sealing the side edge of the belt;

Fig. 7 is a plan view of a portion of the casing taken along line l--'l of Fig. 6 and Fig. 8 is a section similar to Fig. 4, but showing a modified form of wheel.

The device comprises side frames ID and H which are connected by a plurality of cross members l2. A shaft i3 is rotatably mounted in the side frames by means of suitable bearings 39 which bearings also provide a gas-tight seal. A plurality of wheels I4 are mounted on and keyed to the shaft 13 by means of suitable hubs IS. The periphery of each wheel is provided with a groove 16 in which a helical spring I1 is disposed.

The shaft wheels and springs may be fabricated from any suitable corrosion resistant material. For instance, it has been found that Nichrome resistance wire is suitable for the spring IT. The ends of a wire helix of suitable length are welded together to form a loop of a diameter slightly smaller than the diameter of the wheel I 4. Then the loop is snapped into groove l8 and the spring is maintained in the groove by its own tension.

An endless belt i8 is mounted on rollers I9, 20, 2| and 22 which are suitably journaled in the side frames. The belt is of a width approaching the distance between the side frames, and engages the wheels 14 throughout approximately degrees of their periphery. As shown in Fig. 2, a sprocket 23 is provided for roller I9 so that the belt may be driven. Thus, the belt and the Wheels M will rotate in unison, and a print 40 may be fed therebetween as shown in Fig. 3.

A casing 24 is disposed in front of the wheels l4, and the casing comprises generally a top wall, a front wall and a bottom wall. The belt l8 serves as a fourth wall with the result that the casing and belt cooperate to form an enclosed chamber in which ammonia or other gas may be released.

As shown in Figs. 3 and 5, the marginal portion 25 of the bottom Wall is bent so that it lies parallel to the span of the belt at that point, thus providing a seal to prevent the loss of gas. This marginal portion is also provided with bent fingers 26 which extend into the spacers between adjacent wheels and serve as a guide for the prints. Similarly, marginal portion 21 of the top wall forms a seal with the belt and. is also provided with bent fingers 28.

As shown in Fig. 7, the side marginal portions of the casing 24 are extended rearwardly of the marginal portions 25 and 21 to form cylindrical extensions 30 which are aligned with the surface defined by the peripheries of the wheels l4. As shown in Fig. 6, these cylindrical extensions 30 cooperate with the side edges of the belt 18 to provide a seal which prevents the loss of gas. The cylindrical extensions 30 are preferably provided with corrugations 3| which enhance the sealing action. Thus, the casing 24 and the belt l8 are sealed at all points of contact.

Within the casing 24 is disposed a trough 32 to which ammonia water may be supplied through a drip valve 33. Heating elements 34 are disposed beneath the trough 32 and causethe ammonia water to release ammonia. A V-shaped portion of the casing 24 serves as a secondary trough 35 which collects the overflow from trough 32. A drain 35 drains the exhausted liquid out of the casing 24.

In operation, suitable means are provided for driving the sprocket 23 so that the belt may be driven. The shaft 13 and wheels l4 are driven by the belt. The drive is preferably reversible so that prints may be fed either upwardly or downwardly.

When the developer forms an integral component of a complete machine, the prints are fed upwardly from the printer to the developer by means of tapes 37, and the wheels I l rotate in the counter-clockwise direction as shown in Fig. 1. Thus, the print is delivered on to the upper surface of the casing 24, and the fingers 28 serve to guide the prints over the upper surface of the top marginal portion 2?.

At other times, as when the developer is sold as a separate unit, it may be preferable to feed downwardly. Here, the top wall of the casing 24 serves as a feed tray, and the prints are delivered face up on to a suitable guide 38.

In either event, practically the entire surface area of the print 40 is exposed to the action of the ammonia gas that is released within the casing 24, thus permitting much faster operation than is the case with developers of the perforated plate type. As indicated in Fig. 5, the only points of contact with the Wheels Id are those represented by the spots 4|. In the alternative, the springs I! could be eliminated, in which event a line contact would be provided, the peripheral cross section of the wheels I4 being suitably modified, as shown in Fig. 8.

The present arrangement also eliminates sticking since there is no sliding contact with the print and also since what contact there is is of small extent. Furthermore, belt wear is substantially eliminated.

The spring H is preferably formed from a wire of comparatively small diameter and cooperates with a belt l8 having a comparatively hard surface so as to minimize the area of contact between the spring and the print. For instance, the wire from which the spring is formed may be No. 14 gauge which has a diameter of .064 inch. When a disk type wheel is used as shown in Fig. 8,

the edge 42 thereof may be of a comparatively small radius, such as .032 inch. By thus minimizing the area of contact, it has been found that the gas penetrates into the interface between the supportin means and the print with the result that there is at least a partial development of Y 4 the print even at the actual point of contact with the supporting means. Therefore, the spots M are not white, but just a little lighter in shade than the fully developed areas surrounding the same. The same effect is observed when the Fig. 8 arrangement is used except that the line on the print which represents the area of contact is just a little more pronounced.

We claim:

1. A print developer comprising a series 01 wheels disposed in axially spaced relationship, a belt passing around a substantial portion of the periphery of said wheels and cooperating with the same to define a print path so that the concave surface of a print which is advanced along said path will be exposed to the space between said wheels, means for releasing a gas into the space between said wheels so that the concave surface of said print can be subjected to the action of said gas, said wheels being provided with grooves, and helical spring disposed in said grooves to minimize the area of contact between said wheels and said print, said helical springs being in the form of tensioned loops whereby said springs are maintained in said grooves by their own tension.

2. A print developer comprising a series of wheels disposed in spaced axial relationship, a belt passing around a substantial portion of the periphery of said wheels whereby a print can be fed between said wheels and said belt, a casing disposed adjacent said wheels and having cylindrical extensions aligned with the periphery of said wheels, said cylindrical extensions providing side marginal portions for contacting the edges of said belt, and said casing including top and bottom marginal portions contacting said belt at points adjacent said wheels whereby said casing and said belt cooperate with each other to provide a substantially gas-tight chamber in which said wheels are disposed, said side marginal portions being corrugated to provide a seal for the edges of said belt, said top and. bottom marginal portions being provided with bent guide fingers projecting into the spaces between adjacent wheels, means disposed within said chamber for releasing a gas, means for driving said belt in either direction so that a print fed between said wheel and said belt will be exposed to the action of said gas, said wheels being provided with grooves, and helical springs disposed in said grooves to minimize the area of contact between said wheels and said print, said helical springs being in the form of tensioned loops whereby said springs are maintained in said grooves by their own tension.

DAVID R. L. CORNWELL. JOHN TAINI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,075,306 Schade et al Mar. 30, 1937 2,200,451 Kunstadter May 14, 1940 2,457,753 Trump Dec. 28, 1948 2,475,809 Sullivan et a1 July 12, 1949 FOREIGN PATENTS Number Country A Date 586,617 Great Britain Mar. 25, 1947 

